Bladder carcinomas are often surgically excised when they are relatively small in size. It is usually necessary to expand this population of tumor cells in order to perform desired analytical tests on the tissues. This problem has been approached in two ways. First, improvements in the in vitro culture of these tissues has been sought since existing procedures have been of limited value. The method proposed involves analysis of the role of supportive stroma in the growth and control of transitional epithelial cells. The second approach will make use of the athymic nude mouse as a host in which to propagate human tumors in vivo for further analysis. It is hoped that these two techniques will yield sufficient numbers of patient tumor cells for biochemical and immunological analysis of tumor-specific properties. At the same time, an attempt is being made to design a useful in vitro chemotherapeutic drug screening assay so that more effective drug therapy can be applied to each patient. This assay is designed to make use of a minimum of tissue removed at surgery and to provide a drug sensitivity profile within one week of surgery. The assay will involve measure of drug inhibition of specific cellular synthetic processes and will not require long-term growth of the tumor tissue.